An apparatus for air guidance in a processing chamber has a housing with an entrance gate and an exit gate. The system 4 has a database 10 storing entries each relating to recipient parties 6. First threads which cannot execute concurrently are assigned to a first concurrency group. A phase of the sampling clock may be compensated based on the difference between the target slope and the calculated slope. The electronic components of the mobile security system are stored in a primary cabinet in the container so as to be inaccessible from the walkway.